Swimming in open water is dangerous say Derbyshire Police.
Open water such as lakes, reservoirs and other sites like disused, water-filled quarries can be extremely dangerous even for experienced swimmers.
A Derbyshire Police spokesman said: “We are urging people not to go in the water to cool down if the weather is hot as they could endanger their own lives and the lives of others.
“There may be hidden dangers under the surface, strong currents or steep sides.”
Yesterday the force assisted Greater Manchester Police after a 15-year-old boy went for a swim in a river, his body was found later that evening.